It is often necessary due to various spinal disorders to surgically correct and stabilize spinal curvatures, or to facilitate spinal fusion. Numerous systems for treating spinal disorders have been disclosed. One known method involves a pair of elongated members, typically spinal rods, longitudinally placed on the posterior spine on either side of spinous processes of the vertebral column. Each rod is attached to various vertebra along the length of the spine by way of vertebra engaging bone fixation elements. The bone fixation elements commonly include a U-shaped rod-receiving channel for receiving the longitudinal spinal rod therein. Moreover, the rod-receiving channel often includes means for receiving a set screw or closure cap to subsequent clamp and fix the position of the spinal rod with respect to the bone fixation element. With this method, the spinal rod(s) may be shaped to maintain the vertebrae in such an orientation as to correct the spinal disorder at hand (e.g., to straighten a spine having abnormal curvature). Additionally or alternatively, the bone fixation elements may be spaced along the rods(s) to compress or distract adjacent vertebrae.
Surgeons have, however, often encountered considerable difficulty when using this method, due to problems associated with aligning the spinal rod(s) within the rod-receiving channels formed in the heads or body portion of the bone fixation elements. For example, the heads of body portions of the bone fixation elements may be out of vertical and/or horizontal alignment with one another due to the curvature of the spine or the size and shape of each vertebrae.
Thus, there exists a need for a surgical instrument and/or apparatus to help facilitate insertion of the longitudinal spinal rods into the rod-receiving channels formed in the bone fixation elements.